


Captain John Watson, Genetics, and Other Crazy Things

by cyerus



Category: Sherlock (TV), Sherlock Holmes & Related Fandoms
Genre: Crack, Crossover, Humor, M/M
Language: English
Status: Completed
Published: 2012-03-24
Updated: 2012-03-24
Packaged: 2017-11-02 11:43:34
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 5,581
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/368646
Author URL: https://archiveofourown.org/users/cyerus/pseuds/cyerus
Summary: <blockquote class="userstuff">
              <p>The explanation for John "Three Continents" Watson? Jack Harkness is his father.</p><p>Sherlock doesn't know whether he's going to die from jealousy or sexual frustration first.</p>
            </blockquote>





	Captain John Watson, Genetics, and Other Crazy Things

**Author's Note:**

  * Translation into Русский available: [Капитан Джон Ватсон](https://archiveofourown.org/works/621026) by [sKarEd](https://archiveofourown.org/users/sKarEd/pseuds/sKarEd)



> Translation in [Czech](https://johnlockpositive.wordpress.com/2015/07/05/o-kapitanu-johnu-watsonovi-genetice-a-dalsich-prastenych-vecech/) thanks to [miamam](http://archiveofourown.org/users/miamam/pseuds/miamam).
> 
> Thanks to emmessann for the beta and dreximgirl and lady_invidia for the Britpick.

John liked sex.

Sherlock knew this. He accepted it because flatmates put up with each other's annoying habits. Like leaving dirty rugby boots where they could contaminate his mold experiments. Or stealing his violin and hiding it up the chimney. Or wandering around the flat completely starkers.

(That last one wasn't so much annoying as...distracting.)

But this was getting ridiculous.

"How have you been? It's been ages, what have you been doing? Are you a doctor?"

John laughed, eyes crinkling in the corners. "Slow down, Lisa. I'm not going anywhere."

Sherlock rolled his eyes and heroically restrained a sigh. That was the crux of the problem right there: John just couldn't walk down the street without bumping into a former partner of his. Sherlock gave up keeping track of them because there was an entire horde. And they always wanted to talk to John, needlessly delaying Sherlock when he had much better things to do.

(He ignored the little voice that said he could just leave John behind and go off on his own.)

Most vexingly, they kept touching John. Hugging him and patting his arm and kissing him as if he still belonged to them. And quite a few hinted that they were more than willing to rekindle a relationship.

Sherlock carefully didn't think about why that bothered him.

Finally, with one last kiss and a wistful, "Goodbye, John," the woman left.

John watched her go, eyes soft with affection and a little regret. Shoving his hands into his pockets, he canted his head at Sherlock. "Sorry about that. Ready to go?"

Sherlock grunted and strode off, coat billowing dramatically behind him. John bit back a grin at the sight and loped after him.

They walked in silence as they cut through Hyde Park. Sherlock glanced sideways at John, curious despite himself. "You seem to be on unusually good terms with them."

"What?"

"Your former partners," Sherlock clarified. "In my experience, people aren't usually so pleased to see an ex."

"Yeah, well, I try to part on good terms. I liked them, wouldn't have dated them if I hadn't, so I like to make sure they're happy." John shrugged. "It helps that we usually have fantastic break-up sex."

Sherlock blinked.

"No reason for it to be all messy and angry when you can have a damn good shag instead," John added cheerfully.

Sherlock blinked again.

Fortunately, they arrived at the crime scene before Sherlock had to respond. He resolutely pushed any thoughts of John out of his mind and dove into the comforts of murder and mayhem.

 

*

 

"This one's right up your alley. Decapitated builder, found by his friends this morning on site. Forensics doesn't have anything yet."

"That’s because you employ idiots," Sherlock said absently. He had his magnifying glass out and was studying the man's fingernails. "Any witnesses?"

"Sort of."

That got Sherlock to look up, if only to give Lestrade his you-are-an-even-bigger-idiot-than-I-thought glare.

"He means, how can you have 'sort of' witnesses?" John translated.

Lestrade sighed. "His mates might've seen something but they're not talking. I don't think they're too fond of the police."

Sherlock stood up gracefully and snapped his magnifying glass shut. "I'll need to speak to them."

Lestrade snorted. "You're welcome to try."

Lestrade led them to a group of surly-looking men. The biggest and surliest of them all was standing in front of Donovan, arms crossed and scowling.

"Look, I didn't see nothing, so's why don't you stop asking."

"Didn't see _anything_ ," Sherlock corrected tartly.

The man sneered at him. "And who the hell are you?"

For once, Donovan looked glad to see him. She quickly swapped places with him, muttering, "You two deserve each other," and stalked off.

Sherlock studied the man in front of him. Late thirties, married with two children, one of them less than a year old. He was also twice Sherlock's body mass and had arms thicker than his neck.

"You're lying," Sherlock concluded. When the man bristled, he added, "Oh, not about seeing anything, it's obvious you didn't. But you know who did."

The man puffed up and somehow got even larger. It was almost alarming. "Yeah? What makes you so sure, you little toff? You ain't got nothing on me."

"You _don't_ have _anything_ , if you please. I realise the English language is difficult for your tiny little mind to grasp, but do try and make an effort."

The man roared and took a wild swing at him. Sherlock dodged with contemptuous ease, and would have dodged the second punch just as easily if something small and quick hadn't tackled the man to the floor.

John slammed him face down on the ground, knee planted between his shoulder blades. "Do that again, and you won't be using that arm for a very long time," he said, voice soft and very deadly.

There was a moment of silence as the police tried to reconcile their quiet, mild-mannered doctor with this cold-eyed soldier and Sherlock contemplated the strange burst of warmth in his chest.

Lestrade finally cleared his throat. "As an employee of Scotland Yard, I feel compelled to tell you that assault is against the law."

John scowled at him but let the man go. The man scrambled to his feet and whirled around, snarling and swearing fit to make some of the newer police officers blush. He stopped mid-curse as he got a good look at John.

"Johnny?"

John blinked. "Sam?"

Sherlock looked at John, at the slight flush to his cheeks. "Oh, for the love of-"

With a whoop, the man - Sam - pulled John into a bear hug, nearly lifting him off the ground.

John laughed and punched his shoulder. "Let go of me, you wanker!"

Lestrade stared between the two of them as the man rubbed his knuckles over John's head. "You know each other?"

"Biblically," Sherlock muttered underneath his breath.

"Yeah, we- cut that out!" John swatted away a hand nearly as big as his head. "We played rugby together, for Blackheath."

Sam slung an arm around his shoulders. "What are you doing here? I thought you were a doctor?"

"I am. I, uh, help out the police in my spare time. My friend does, actually. He’s the one you tried to flatten."

Sam raised a brow as he looked Sherlock over. "Friend, huh?"

"Shut it." John shoved at him. "It's not like that."

"Sure it isn't, Johnny." Sam ruffled his hair. "What d'you need?"

"Did you see anything strange going on?"

Sam rubbed his chin. "No, but I wasn't here yesterday. Charlie was, though." He turned and bellowed at the men loitering around. "Oi, Jack! Find Charlie and bring him back here, yeah?"

"Cheers, Sam."

"Anything for you, Johnny."

John grinned up at him, bright and happy, and Sam melted. For one terrible moment, Sherlock thought the overgrown oaf was going to kiss John.

To his immense relief, the man just patted John on the shoulder. With a soft, "It's good seeing you again, Johnny," he lumbered off.

John stuck his hands in his coat pockets and rocked back on his heels. Sherlock made his way to him and glared.

"What?" John asked defensively.

"Did you," Sherlock asked in a clipped tone, "shag half of London?"

John rolled his eyes. "Don't be ridiculous, Sherlock. I haven't been in London for that long."

Sherlock stared. "Was that a joke?"

John walked off.

"John?"

 

*

 

Mycroft was managing a very delicate situation. He had spent the past week politely chatting with the South African ambassador. She was cold, collected, and showed about as much emotion as a brick wall. They had whiled the morning away playing words games and carefully navigating the minefield of conversation, and were working their way well into lunch.

The last thing he needed was for his brother to storm into the private room of a very exclusive restaurant.

He made a mental note to fire his bodyguards.

"Sherlock, I'm in the middle of a very important meeting-"

"Where did you put it?"

"Put what?"

"You know what!"

Mycroft sighed and waved away his men. "My apologies, Madam Ambassador. This is my brother, Sherlock. I'm afraid manners aren't one of his strengths."

The ambassador quirked her lip. "That is quite all right, Mr. Holmes."

Oh, she was enjoying this. Mycroft valiantly restrained the urge to strangle his brother. "Sherlock, whatever you think I did, we can discuss it later."

Sherlock crossed his arms, face set in a mulish expression.

"Don't make me order my men to drag you out of here, Sherlock. It will be most unbecoming."

The ambassador was laughing at him. Not a single muscle in her face had shifted, but Mycroft could tell.

"Amahle?"

Three heads looked up. John stood awkwardly in the doorway, smiling hesitantly.

In the split second that Mycroft looked away from her, a body double swooped in and replaced the ambassador. At least, that was the only plausible explanation Mycroft could come up with to explain why the ambassador, who he was starting to suspect was an advanced android, was smiling like it was Christmas, her birthday, and Imaginary South Africa Won The World Cup Day combined.

Mycroft was, he had to admit, a little unnerved.

"John! Sawubona!"

She held out her hands, and John strode over and clasped them warmly. "Sawubona, Amahle. How have you been?"

"Good, John. Very good." She beamed at him. Actually _beamed_.

Mycroft cleared his throat. "You two have met before, I take it?"

The ambassador didn't even look at him. "Yes. We have."

"How?" Sherlock demanded. "Nothing in your service record says anything about South Africa."

"When did you see my-" John shook his head. "Never mind. I don't want to know. There was a program in medical school. I spent a summer in Cape Town, it's where I met Amahle."

"Yes. I was very fortunate to have met John Watson." She looked him over fondly, and _fuck_ a _duck_ , her eyes were softening in a way that Sherlock was becoming alarmingly familiar with.

"Right, that's it, we're leaving." Sherlock grabbed John by the collar of his coat and started dragging him away.

"What- Sherlock!" John dug both heels into the floor. "What are you doing?"

Sherlock scowled at him. "Don't be thick, John. Murders don't solve themselves."

"Well, at least let me say goodbye. It's, you know, the polite thing to do?" John's tone made it very clear that it wasn't a request.

Sherlock grudgingly let go. He crossed his arms and turned his back, decidedly not listening to John and the ambassador murmur sweet nothings to each other. And he most definitely did not hear a lingering kiss.

"Have a good life, John."

"You too, Amahle."

A hand touched his elbow, and Sherlock stalked off without looking back. John fell into step beside him, warm and familiar.

They were halfway back to Baker Street before Sherlock finally exploded. "Africa, John?"

"What about it?"

"You're not content with shagging all of Britain, but you had to do Africa as well?"

John shrugged. "Among others."

Sherlock stopped in his track. "What?"

John kept walking and called over his shoulder. "I got my leg over three continents, Sherlock. You should ask Bill about it sometime. He's got stories."

"I- You- _What_?!"

 

*

 

Bill Murray had called John a "dirty boy" on his blog.

Biggest. Understatement. Ever.

There was the familiar cry of, "John! John Watson, is that you?" A tall woman jogged over, dragging a man by the hand (husband, happily married ten years, no kids, two dogs).

What was more unusual was her flinging herself at John and kissing him.

Well, no, kissing wasn't right. She was devouring him, one hand gripping the back of his neck and the other firmly squeezing his arse. John, for his part, made blissful noises and responded enthusiastically, doing something with his tongue that made her issue a positively indecent moan.

Sherlock gaped at them, torn between ripping John away and pointing out that the woman's husband was _right there_ , and that his face was turning an alarming shade of red.

The man lunged forward and pulled his wife away, then shoved John against a wall. Cold fury uncoiled up Sherlock's spine and hetook one menacing step forward.

The man shoved a knee between John's legs and proceeded to snog the living daylights out of him.

Sherlock nearly tripped over himself.

He stared, frozen to the spot, stomach twisting as the image was seared into his brain: John groaning, head thrown back, thrusting lightly against another man's leg. One of the man's hands disappeared between their bodies and John let out a deep growl that went straight to Sherlock's groin. Then John flipped them over and shoved his hands up the man's shirt. Goodness knew what he did next because the man's legs buckled and he would have fallen if John hadn't been pinning him to the wall. Large hands fumbled at John's zip and Sherlock knew the man was seconds from dropping to his knees, with no regard to the scandalised passers-by or the constable eying them suspiciously from down the street.

Sherlock's vision went red.

He was halfway to forcibly separating the two when John pulled away and gently disentangled himself. Licking swollen lips, John grinned at the couple. "Hullo, Mary, Ryan. Hell of a greeting."

Mary laughed and hugged John. "Can you blame us? We haven't seen you in ages!"

Sherlock scowled. Striding forward, he shoved John behind him and loomed. The couple started and stared at him as if noticing him for the first time. John rolled his eyes and stepped beside him.

"Don't mind him, I haven't gotten him house-trained yet. Mary, Ryan, this is my flatmate, Sherlock Holmes. Sherlock, this is Ryan and Mary Benson. Old friends of mine."

"Friends," Sherlock said flatly.

Ryan grinned at him. "From uni." He reached over and tousled John's hair. "This man got Mary and me together. We can't owe him enough."

John huffed good-naturedly and batted at his hand. "Stop that. I didn't do all that much."

Sherlock studied them with narrowed eyes. "You're not bothered that he's had sex with both of you."

Most people would have been offended, or at least uncomfortable. This couple beamed at him.

"Yeah, Johnny thought we'd be good together, so he invited us to his flat for a shag." Ryan looked at his wife adoringly. "We hit it off immediately."

Sherlock looked at John, to the couple, and back to John. John smiled blandly.

_He didn't. That's just, why would he, I mean, that's not sanitary. Surely not. At the same time?_

"I think the term you're looking for is 'threesome,'" John said helpfully.

Mary sighed nostalgically. "You were so beautiful between us."

 _Oh dear god_ , thought Sherlock, distantly horrified.

Ryan cleared his throat. "Speaking of, are you with anyone right now?"

_Oh. God._

John was tempted. Sherlock could tell, from the way he licked his lips and peered up at them from beneath lowered lashes. A different sort of horror squeezed his heart.

Just as Sherlock was about to scoop him up and run off with him, John sighed and reluctantly shook his head. "Sorry, I'm- Well, it's a bit complicated right now."

They were obviously disappointed but accepting. After a few more well-wishes and invitations to dinner, they parted ways.

Sherlock and John continued back to the flat. Sherlock was silent, his mind whirring, taking in this new information about John. He shouldn't be surprised, he knew John had a very liberal view on sex. Then again, he didn't realize it was that liberal. And what that woman had said. Unbidden, an image crossed his mind, John moaning and arching between two bodies-

Pain exploded in his head.

 

*

 

White spots were dancing happily in his vision. Sherlock blinked past them to see John's worried face.

"Sherlock?"

He was lying flat on his back on the pavement. John was kneeling next to him, hands hovering over his face.

"Sherlock, can you hear me?"

Sherlock grunted and struggled to push himself up. "Don't ask stupid questions, John."

Concern gave way to exasperation, and John shook his head. "Well, at least your charming personality is intact." John helped him sit up and brushed his hair out of his face. Gently, he probed Sherlock's forehead. "Any dizziness or nausea?"

Sherlock swatted his hand away, irritated. "I'm fine." At John's doubtful look, he added, "I know what a concussion feels like. I don't have one."

John frowned at him. "All right. But I'm keeping you under observation."

"Do as you will."

A small crowd was gathered around him, and a young woman was asking if she should call the ambulance.

"No, it's fine. I'm a doctor, I can manage." John helped him to his feet, and Sherlock found himself leaning on him for a few seconds.

Two teenagers in front of him were giggling. Sherlock narrowed his eyes and studied the people around him. Some avoided his eyes, others were hiding grins. One elderly man was outright laughing.

"John, what happened?"

There was a pause. Sherlock turned to look at him, only to find him staring at the ground like it was the most fascinating thing in the world.

"John?"

"You, uh." John glanced at him, the corners of his mouth twitching.

Sherlock glared at him.

"You walked into a streetlamp."

There was a long moment of silence, broken by the man's cackling.

"You were distracted?" John offered.

Sherlock's glare turned glacial. Wrapping his coat around him, he stalked off.

 

*

 

John didn't look up from his laptop. "Why are you staring at me like that?"

"Hm?" Sherlock pulled himself out of his thoughts. "Like what?"

"Like I'm a crime scene."

"Ah." Sherlock leaned back in his armchair. "I'm trying to figure out what you look for in a sexual partner."

John blinked. "Okay. Why?"

"I've met a number of your ex-partners. There's a large variation in their characteristics and I'm trying to see if there's a pattern."

"Oh."

"Yes."

"Well?"

"Well, what?"

"What's my type?"

"Willing. And with a pulse."

"Thanks," John said dryly.

"I believe the term is 'slag.'"

"Hey!"

"It's an accurate description, isn't it?"

"Look," John growled, slamming his laptop closed, "I like sex. I'm good at it, and I like making people feel good. I'm a perfectly healthy adult human with a perfectly healthy sex drive. So piss off."

Grabbing his laptop, John made to go up to his room.

"How good?"

John paused despite himself. "What?"

"You say you're good at sex. Most people do, no one wants to admit that they're terrible in bed." Sherlock narrowed his eyes and canted his head. "So how good are you, really?"

John turned and gave him a long once-over. Sherlock's breath caught in his chest as John smiled slowly, lazy and wicked.

"Very."

With that, he was gone. Sherlock was left sitting alone, with a dry throat and uncomfortably tight trousers.

 

*

 

The thing was, John wasn't having sex. At least, not that Sherlock could tell.

There was that bit with Sarah, but the relationship fizzled before he got past the sofa stage. After that, John didn't make the effort to find anyone else. He flirted on occasion, but more for fun than anything else, and he never accepted any offers.

And, to Sherlock's increasing disgust, he got plenty of offers. So much that Lestrade and his band of merry idiots were starting to look at John with a mixture of befuddlement and awe. Some of the constables were taking notes.

Sherlock was jolted out of his contemplation as John padded into the kitchen. Fresh from the shower, still damp and steaming, wearing nothing but a warm smile.

Sherlock quickly turned his back and ignored him.

"And a good morning to you too," John said cheerfully.

As John passed behind him, Sherlock caught a whiff of his aftershave. No, not his aftershave, something else. A heavy musk that wrapped gently around his mind and muted his senses, smothering his thoughts in warm velvet. An image drifted across his mind, of petting a purring tiger while wearing leather gloves. Or rolling around Egyptian sheets in silk pajamas.

"Sherlock? Sherlock!"

Sherlock blinked slowly, finding that his vision was loathe to focus.

The first thing he noticed was that he was oddly damp. As if he had been holding on to a wet towel. Or his naked flatmate.

His nose was also buried in John's hair and he was pressing his erection rather unsubtly into John's arse.

"Er."

John sighed and shook his head. "No, sorry, it's my fault. I forget to put something on sometimes."

Sherlock's brain was under siege from more testosterone than it knew how to handle, so it took him a moment to figure out what John was saying. "You smell like this naturally?"

John flushed. "Yeah, more or less."

Sherlock propped his chin on the wounded shoulder, unconsciously tightening the arm around John's waist. "That's why you always wear cologne, even when we're alone in the flat."

"Yeah." John shifted a little, then leaned back into Sherlock's chest. "It's, well, I guess you can call them pheromones. They tend to get people excited. Cologne's good at hiding it, or a decent aftershave. It's hell on the wallet but it's better than being tackled every time I stick my head out the door."

"Mm," Sherlock hummed distractedly. He nuzzled John behind an ear and gently bit the nape of his neck.

John shuddered and tilted his head back, baring his throat. "Sherlock."

Sherlock's mobile went off.

John nearly stumbled as Sherlock abruptly dropped him. Somewhat disgruntled, he watched as Sherlock bounded across the sitting room and snatched up his mobile.

"It's Lestrade. There's been a murder." Sherlock grinned gleefully and bounced on his toes.

"There's always a murder. We're getting to be as bad as the States," John grumbled. "I'll just go get dressed."

"Do try and hurry, John," Sherlock said distractedly, already typing away. "I want to get there before Anderson ruins the scene."

John huffed and trudged up the stairs. Sherlock waited until he heard John's bedroom door shut, then sighed and rubbed his forehead.

He was a genius. He saw things and made connections that normal people, with their tiny little brains and narrow minds, would never comprehend. He knew why John wasn't on the pull. Hadn't been, for months.

John was waiting for Sherlock.

And Sherlock, judging from his responses to John (ranging from rage, jealousy, and rampant possessiveness to a warm fuzziness that he, much to his horror, suspected was comparable to the normal human response to puppies and kittens), wanted him back.

But relationships were messy and required more effort that Sherlock was willing to give. He and John were comfortable where they were, it wasn't worth disrupting it just for a shag.

No matter how good John was in bed.

Absolutely brilliant, if his previous partners were any indication.

Damn.

 

*

 

Sherlock contemplated the body before him.

Lestrade crossed his arms. "Got anything for me?"

"It's not a mask. Perhaps some kind of plastic surgery, but the level of sophistication required is not achievable with current technology."

"Yeah, I figured that when we found a bloody fish-man."

Sherlock ignored him and peeled back a fin. "There was a rip here, in the webbing, but it was healing. Look, you can see the scab. This isn't a prosthetic, it's real." Sherlock sat back on his haunches, eyes shining. "A new species. How fascinating."

"Yeah, brilliant." Lestrade sighed. "Christ, this is going to take so much paperwork."

John ambled over with a cheerful, "So, Sally's been telling me you caught the creature from the Black Lagoon."

Lestrade waved at the body. "See for yourself."

John peered over Sherlock's shoulder and stiffened. "Oh."

Sherlock twisted to give him a sharp look. "'Oh?'"

"Um, yeah?"

Sherlock stood up and loomed over John. "You're not surprised."

"Of course I am, it's-"

"No," Sherlock cut him off. "The normal reaction would be shock, closely followed by denial. You've gone straight into accepting it, which begs the question, why?" Sherlock stepped closer and gazed into wide blue eyes. "You recognize it, don't you?"

"Hold on!" Lestrade eyed John suspiciously. "You've seen one of these before?"

John shifted uneasily under their twin glares. "Sort of. I mean, I've seen pictures. I think they're called blowfish?"

"Blowfish," Lestrade said flatly.

"Um, I can't really tell you more. Official Secrets Act and all that." John rubbed the back of his neck. "If it's any consolation, you won't have to deal with it. He'll be here soon."

"' _He_?'"

A large black SUV roared onto the scene, coming to a stop with an earsplitting screech. Sherlock watched with mild interest as a horribly mismatched group of people piled out, lugging equipment that he had never seen before.

"Oi!" Donovan barred their way. "You're not allowed here without proper clearance."

The man in the lead smiled at her and offered her a badge. "Captain Jack Harkness, Torchwood Three. We've got clearance. Although-" his voice dropped into a deep purr, "-I would be happy to discuss it with you further."

Donovan blinked and slowly accepted the badge. She stared at it for a long moment, as if trying to remember the English language.

"Yeah, it- everything looks in order."

Harkness winked at her. "Thank you, sergeant."

John had his face buried in his hands. Sherlock glanced at him, then back at Harkness. He was coming their way, coat flapping dramatically behind him.

Lestrade cleared his throat and stepped forward. "Detective Inspector Lestrade. I'm in charge of this investigation."

The man smiles charmingly. "Captain Jack Harkness. We'll take over from here." He stuck out a hand and raked appreciative eyes over Lestrade's body. Lestrade flushed and shook his hand, perhaps holding on a little longer than necessary.

Harkness' grin turned absolutely filthy. "Although, if you want to stick around and lend a hand-"

"Oh, don't start!" John snapped.

Harkness jerked in surprise, then a genuine smile graced his face. "Johnny!"

Sherlock nearly screamed in frustration as Harkness pulled John into a hug and planted a kiss on the top of his head. Seriously? At every crime scene? Shouldn't John run out of exes at some point?

One of Harkness' team, a small, angry-looking man, must have felt the same, because he started swearing. "Goddamit, Harkness, will you stop groping your old shag and get to work?"

"Owen," one of the women scolded. Welsh, from her accent.

"Don't look at me, blame the tea boy!" Owen gestured sharply at the young man, the only one wearing a suit. "If he kept him satisfied we wouldn't have to deal with him flirting with everything and anything with a pulse!"

The young man didn't even look up from where he was unrolling a body bag. "I can kill you in so many different ways. They'll never find your body."

"Huh." John's voice was muffled, swamped as he was in the folds of Harkness' greatcoat. "And here I thought your people couldn't get any worse."

Harkness laughed and ruffled John's hair. Sherlock clenched his hands into fists and reminded himself that flinging himself at another man in a jealousy-fueled fury was beneath him.

"Ianto, no killing Owen unless I give you permission. Owen, guess who gets to clean Janet's cell for the next month?" Harkness called over his shoulder.

Owen dropped his kit and cursed. "What, because you can't keep your hands to yourself?" He stomped over and sneered as John extricated himself from Harkness' grip. "Though, you're slumming a bit with this one, aren't you, Harkness? Not exactly a looker."

Sherlock's rage identified a new target.

"Shut up, Owen," Harkness answered lazily. He wrapped an arm around John's shoulders and pulled him into his side. "This is my son, John Watson. Johnny, this is Owen Harper. He's a doctor too."

"Charmed," John said dryly. "Please tell me Dad doesn't let you near people."

What?

Wait, what?

"Your son?" Donovan looked between the two of them. "But, you can't be more than a few years older than him!"

Harkness laughed and winked rakishly. "Superior genes, love. Johnny here took after his mother, unfortunately. Her side of the family looks like they belong in a care home before they're twenty-five."

"Thanks, Dad."

Harkness' team exchanged looks.

Sherlock couldn't even begin to decipher the subtext to their silent communication and didn't particularly care. This new facet of John Watson was just mind-boggling. Not only was Harkness lying, but Donovan had actually managed to land on the most salient point. There was absolutely no way Harkness could have fathered John, not unless he had somehow gone back in time or found the fountain of youth.

Not to mention he was _American_.

"And who are you?" Sherlock blinked as six feet of man all but pressed up against his front, interrupting his train of thought.

"My flatmate. Sherlock Holmes." There was something off about John's voice, but Sherlock couldn't figure out what. His brain didn't seem to be functioning properly.

"Sherlock, huh?" Harkness looked him over and Sherlock got the distinct feeling that he wasn't so much undressing him with his eyes as making a full length pornographic feature. "Knew a Sherlock once. Spent three days in a hotel with him, never left the room."

Sherlock made a noise suspiciously like a whimper. Harkness leaned in close, and good lord, he obviously didn't bother with masking his scent-pheromones-whatever because Sherlock was bludgeoned over the head with pure unadulterated silk pajama-clad tigers.

Harkness grinned and moved in further and Sherlock could only watch helplessly as his lips came in closer, and oh, he was going to be snogged by John's father, and wouldn't that be awkward when he finally shagged Jo-

John neatly stepped in between them and firmly pushed Harkness back. Sherlock found himself clinging to John for the second time that day, one arm wrapped around his waist and the other around his shoulders. He vacillated between a "keep the bad, bad man away from me" hold and "I've been inappropriately turned on by your father and really want to take you right here on the pavement" one.

John crossed his arms with some difficulty and scowled at his father. "Stop it," he growled.

Harkness gave him a wounded look. "I was just saying hello."

John raised a brow, unimpressed. "That's what you said right before you shagged my roommate back in uni. And half the rugby team."

Owen snorted. "Only half?"

"Well, Johnny had already gotten the other half. I couldn't have sex with them." Harkness wrinkled his nose. "It would have been weird."

John rolled his eyes. "Yeah, _that_ 's the weird part."

The police and Harkness' team were looking back and forth between father and son like they were spectators at a rather vicious tennis match.

"Sir?" The suited man politely cut in. "I hate to interrupt but the blowfish is starting to liquefy. And it's eating through the ground."

"Oh, damn. All right kids, back to work." Harkness clapped his hands once. "Owen, Gwen, help Ianto get it contained. Tosh, take readings of the area, make sure there aren't any other surprises."

Getting their orders, Harkness' team got to work. The police stood by, watching them with varying degrees of bemusement and general what-the-fuckery.

Harkness paused to ruffle John's hair. He tactfully avoided touching Sherlock, which was all the more impressive considering Sherlock was stuck to John like an over-friendly octopus.

"It was good seeing you again, John-boy."

"You too, Dad."

"If you're ever in Cardiff, you should stop by."

"I will."

Harkness leaned in and kissed John's forehead. As he straightened, he caught Sherlock's eye and winked. "Have great sex!"

Sherlock could only stare as Harkness bounded off with a swoosh of his coat. John shifted in his arms and craned his head up to look at him. "Uh, Sherlock? You mind letting go?"

Sherlock looked from John, to Harkness, and back to John. With a sigh of defeat, he unwrapped himself from around John and ran a hand over his face.

"Fine. Fine! Let's have sex."

 

*

 

Sherlock stared at the ceiling. "Oh."

John made a contented sound and scooted closer. He tucked his head under Sherlock's chin and flung an arm across his chest.

Sherlock tried again. "Is it always like this? With you?"

"Hm, yeah." John drowsily nuzzled his neck. "Told you, I'm very good."

"Ah. Yes."

Sherlock couldn't think of anything else to say, and really, did it matter? They were in John's bed and John was curled up against his side, pliant and warm and sated. The room reeked of sex and John's pheromones, and Sherlock could feel his prick stir in interest.

Which was ridiculous. He wasn't seventeen anymore, he had a decently long refractory period. And that wasn't taking into account the fact that he had already come twice.

John sighed and dragged a leg over Sherlock's waist. Sherlock swallowed as his cock bumped up against John, right behind his balls. John moaned softly and thrust down lightly, until the glans was pressed right up against his hole.

His tight, messy hole, the one Sherlock was buried in just a few minutes ago. John was probably still loose and slick from the ferocious fucking he had given Sherlock. All Sherlock had to do was slide in.

Sherlock winced as his cock went from half-interested to rock-hard in seconds. John chuckled and leaned up to give him a long, filthy kiss.

"Care for another go?

"Oh, _god yes_."


End file.
